Question 1008282
A gondola conductor charges $2 per yodeler and $1 per xylophone. It cost $40 for the entire club including xylophones to ride the gondola. 2 yodelers can share a xylophone, so the number of yodelers on the gondola is twice the number of xylophoners. How many yodelers and xylophoners are on the gondola? 
I wrote it as:
x= xylophoners 
y= yodelers
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Equations:

Quantity Equation::y = 2x
Value Equation::  x+2y = 40 dollars
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Rearrange to use the subtraction/addition method
2x - y = 0
x + 2y = 40
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Modify::
2x - y = 0
2x + 4y = 80
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Subtract and solve for "y":
5y = 80
y = 16 (# of yodelers)
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Solve for "x"::
x = 2y
x = 32 (# of xylophoners)
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Cheers,
Stan H.
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